1. Field of the Invention
The present invention is concerned with a method for carrying out an electrolysis process in an aqueous or organic solution or in a melt.
The invention is also concerned further with an apparatus for carrying out the method.
2. Description of the Prior Art
Electrolysis processes along with suitable apparatus necessary for carrying them out are known in the technology in numerous variants. Examples are electroplating, i.e. the application of galvanic coatings to metallic and nonmetallic surfaces, and the countless methods of metal extraction and metal refining both in aqueous solution and in the melt. Further, electrolysis finds application in organic and inorganic chemistry for the purification of liquids, especially waste liquors and waste water, where in most cases harmful substances in solution must be precipitated or separated by ion discharge or a synthesis carried out. The carrying out of the method and the equipment and installations required are known from the literature (e.g. C. L. Mantell: "Electrochemical Engineering", McGraw Hill Book Company Inc., New York/Toronto/London, 1960; R. W. Houghton and A. T. Kuhn: "Mass-transport Problems and Some Design Concepts of Electrochemical Reactors", Journal of Applied Electrochemistry 4, 1974, pp. 173-190; P. M. Robertson, F. Schwager and N. Ibl: "A New Cell for Electrochemical Processes", Journal Electroanal. Chemistry 65, 1975, pp. 883-900; P. M. Robertson, N. Ibl: "Electrolytic Recovery of Metals from Waste Waters with the `Swiss-roll` Cell", Journal of Applied Electrochemistry 7, 1977, pp. 323-330; P. Gallone: "Achievements and Tasks of Electrochemical Engineering", Electrochimica Acta 22, 1977, pp. 913-920). The required cell voltages range from a few tenths of a volt to a few volts, and in exceptional cases ten times higher, while the current strengths can amount to from a few mA to a hundred kA and more. In all the aforementioned examples of application, the potential difference needed for the electrolysis cells is obtained from an external source of electrical energy and impressed on the electrodes via suitable fixed, detachable or movable contact systems. The contact points and current leads of the electrolysis installations in general constitute important components determining both method and construction. At different times electrolysis cells with moving, in particular rotating, electrodes also have been designed for both industrial electrochemistry (e.g. in cadmium extraction) and laboratory purposes.
All conventional electrolysis methods and the corresponding equipment for carrying them out find themselves confronted with the intricate problem of energy input, which is more critical with higher desired cell outputs and higher current strengths. This holds true quite generally for all methods regardless of whether fixed, movable or detachable current leads or even rotating electrodes are provided. In the case of the latter the advantages of the favorable conditions created by the relative motion between electrodes and electrolyte can often not, or only partly, be made use of, since a constant and controlled energy input and potential maintenance is practically impossible with sliding contacts. This disadvantage is more important the higher the requirements on selectivity desired from the process side.